Sean C. Morgan
Highway 20 will close Tuesday, Aug. 2, for two months to allow repairs for Sheep Creek Bridge and its abutments, which have been damaged by an active landslide.
The highway, a key east-west route through central Oregon, will remain closed through the end of September.
The bridge is located 26 miles east of Sweet Home at milepost 56.6. Its eastern abutment rests on an active landslide, where recent earth movement has been measured at 6 to 7 inches per year.
The bridge was designed and built to move with the slide, but it has reached the point it must be replaced, said Angela Beers Seydel of the Oregon Department of Transportation. .
ODOT has periodically adjusted the bridge back into place, but now it can be adjusted no further. Further movement of the landslide has damaged the bridge, although it has remained usable over the past year.
During the first phase of the project, in 2015, ODOT drove 50-foot steel piles into the ground above the bridge to redirect the slide around the abutment.
The second phase is intended to stabilize the existing structure and eliminate further sliding, Beers Seydel said. The new bridge span and abutment will be built to ride on top of the slide if it keeps moving, making the impact to the bridge more consistent, predictable and manageable.
The abutment on the slide will function differently from the old mechanism, Beers Seydel said. “It basically rolls over the slide.”
Highway 20 will remain open between Sweet Home and the west end of the bridge and from the Santiam Junction to the east end of the bridge. That means the majority of the U.S. Forest Service campgrounds east of Sweet Home will continue to be open and accessible, she said.
“The big thing for folks in Sweet Home to know is they can get to their favorite places.”
Access to popular trailheads in the Middle Santiam Wilderness and to Shedd Camp Shelter is available via Forest Service roads 2047 (Sheep Creek) and 2041 (Soda Fork). To get to Iron Mountain and Cone Peak trails, visitors will need to approach on Highway 20 from the east. All campgrounds located along Highway 20 will remain open.
Forest Service officials do not recommend that motorists use forest roads to bypass the closure.
Motorists who choose to take Forest Service roads to get around the highway closure do so at their own risk. No alerts of potential hazards will be posted. Remote Forest Service roads are not maintained for passenger car travel and are generally narrow with blind corners and few pull-outs. When traveling on Forest Service roads, motorists should carry a detailed map of the area and be vigilant for log trucks, other vehicles and hazards.
“I haven’t been on all of them, but quite honestly, the network of roads can be confusing,” said new District Ranger Nikki Swanson. “I’d hate for someone to get out there and lose their way.”
She added that many of the forest roads have potholes and other problems.
“I wouldn’t take my own passenger car on those roads,” she said.
Detour signs will direct travelers to use highways 22 and 126. There will be no local detours.
As a public safety measure, Forest Service Road 2043 will be closed to public use. It will be reserved for emergency service access during the highway closure.
“That’s their route to get around,” Swanson said. “If people block it with RV’s or trailers, that could set up a dangerous situation.”
The road closure will also halt the Clear Lake Shuttle bus service, which has been offered on weekends since Memorial Day, director Ken Bronson said.
The closure will last six to eight weeks, finishing by the end of September, but construction will continue at the bridge through October.
“You’re going to start seeing people staging stuff, getting materials up there,” Beers Seydel said.
People have been positive about the project, she said, once she explains what’s happened to the bridge over the years and they learn “it was all built on a big landslide.
“We appreciate that folks understand why we need to close the road.”
Further information is available at https://www.oregon.gov/ODOT/HWY/REGION2/Pages/US-20-Sheep-Creek-Bridge-Phases-1-and-2–.aspx.
To obtain maps or directions to recreation areas on the east and west side of the closure, stop by or call the Sweet Home Ranger Station at (541) 367-2367 or visit http://www.fs.usda.gov/willamette/. Stay up-to-date on Forest activities by following us on Twitter and Facebook @willamettenf. Additional information can also be found at http://www.linnparks.com/hwy-20-closure-and-access/.